1. Field of the Invention
The present invention relates generally to energy efficient Ethernet networks and, more particularly, to energy efficient Ethernet with asymmetric low power idle.
2. Introduction
Energy costs continue to escalate in a trend that has accelerated in recent years. Such being the case, various industries have become increasingly sensitive to the impact of those rising costs. One area that has drawn increasing scrutiny is the IT infrastructure. Many companies are now looking at their IT systems' power usage to determine whether the energy costs can be reduced. For this reason, an industry focus on energy efficient networks has arisen to address the rising costs of IT equipment usage as a whole (i.e., PCs, displays, printers, servers, network equipment, etc.).
In designing an energy efficient solution, one of the considerations is the utilization of the network link. For example, many network links are typically in an idle state between sporadic bursts of data. The transmission of idle signals on a link wastes energy and adds to the radiated emission levels. Identification of these frequent low link utilization periods can therefore provide opportunities to produce energy savings.
In other network links, however, the traffic profile can include regular or intermittent low-bandwidth traffic, with bursts of high-bandwidth traffic. Here, identification of a low link utilization period is more difficult and the potential for energy savings is reduced.
Conventionally, an energy efficiency control policy in a network device is operative to analyze the link utilization to determine whether to enter a low power idle mode to save power. As data from the two different sides of the link do not necessarily appear at the same time, identifying an opportune time to enter a low power idle mode can be difficult. What is needed therefore is a mechanism that can maximize energy savings when considering the asymmetric nature of link utilization.